German prosecutors have opened investigations against Deutsche Bank co-CEO Juergen Fitschen and management board member Stefan Krause to probe tax evasion involving the trading of carbon emission certificates.

Fitschen, who took over the reins of Germany's largest bank together with India-born Anshu Jain in June, is the highest ranking official to become the focus of an ongoing probe into the role of some employees of the bank in tax evasion and money laundering related to the EU carbon trade scheme.

Some of the employees of the bank have been charged with helping its clients to evade taxes estimated at over 300 million euros.

The prosecutor's office in Frankfurt said on Wednesday it decided to extend its investigations to Fitschen, Krause and some other employees of the bank to determine whether they are hiding any relevant evidences related to tax evasion and money laundering.

Altogether 25 Deutsche Bank employees are currently under investigation and arrest warrants were issued against five of them, chief prosecutor Guenter Wittig said in a TV interview on Wednesday night.

Earlier on Wednesday, over 500 police officials and tax inspectors raided the headquarters of Deutsche Bank in Frankfurt as well as its branches and private properties in Berlin and in Duesseldorf.

The investigators charge that between 2009 and 2010, Deutsche Bank had helped an internationally operating ring of traders to buy emission certificates abroad without paying the value added tax and to sell them among each other, enabling them to receive the tax returns legally.

Fitschen and Krause had signed Deutsche Bank's tax declaration in 2009.

Fitschen headed the bank¿s German operations at that time while Krause was the chief financial officer

The EU's emissions trading system to reduce CO2 emissions, sets limits on the emissions of industries and power plants and allows them to buy carbon permits for additional emissions if needed as well as to sell their surpluses.

In December, last year, a judge at the regional court in Frankfurt sentenced six men of different nationalities to jail after finding them guilty of tax evasion in emissions trade between 2009 and 2010.

Investigations at that time showed that Deutsche Bank staff had cooperated with them.

Deutsche Bank confirmed Wednesday's police raid and said it would continue to cooperate with the authorities.

In a statement, the bank said Fitschen and Krause were involved in the investigations as they